#Alan Kaplan
#10-16-17
#ver 1.1 fixed pick by nameadds default sort of displayname
#requires -module GroupPolicy
#requires -version 3

Add-Type -assemblyname Microsoft.visualBasic 

function Edit-GPO([guid]$guid, [string]$domain){
    #Based on 
    #http://blog.backslasher.net/opening-group-policy-management-editor-from-the-command-line.html
    $odomain = Get-ADDomain $domain
    # Operate on PDC to help consistency
    $server=$odomain.PDCEmulator
    $PoliciesPath=("CN=Policies,"+$odomain.SystemsContainer)
    $GPPath= "LDAP://{0}/CN={{{1}}},{2}" -f $server,$guid,$PoliciesPath
    gpme.msc "/GPOBJECT:`"$GPPath`""
}

Function Get-GPOList{
    Write-Progress "Reading the list of group policy objects in $domain.  Please wait ...."
    $list = Get-GPO -All -server $domain  -Domain $domain  | 
    sort displayName | 
    Select-Object -Property DisplayName,Owner, GPOStatus,ID #-OutVariable list
    
    Write-Progress "Done" -Completed
    $selected = $List |Out-GridView -OutputMode Single -Title "Select GPO to edit, then click OK"  
    if ($selected)
    {
        ($selected).id.Guid.ToString()
    }
    Else
    {
        ''
    }
}

$domain = [Microsoft.VisualBasic.Interaction]::InputBox("Edit a GPO in what domain?", "Domain", "$env:userdnsdomain")
if ($domain.Length -eq 0)   {Exit}

#message for Welcome menu
$msg = "This script lets you directly launch the Group Policy Editor.`n
Enter a GPO GUID, DisplayName, or enter `"List`" pick the GPO from a list."

$strInput = [Microsoft.VisualBasic.Interaction]::InputBox($msg, "Choose Action")
if ($strInput.Length -eq 0)   {Exit}

$strInput = $strInput.Trim()

if ($strInput -match 'list')
{
    $guid = Get-GPOList
}
ELSE
{
    #Logic to check whether the input is a GUID or string
    $ok = [guid]::Empty
    $bIsGuid = [guid]::TryParse($strInput,[ref]$ok)
    if ($bIsGuid)
    {
        $guid = ([guid]::Parse($strInput)).guid
    }ELSE{
        Try{
            $guid = (Get-GPO -Name $strInput -Domain $domain -ErrorAction stop).id
        }
        Catch
        {
            Write-warning "Could not find `"$strInput`" in $domain, getting GPO list instead."
            $Guid = Get-GPOList
        }
    }

}

if ($guid.Length -ne 0){
    Edit-GPO $guid $domain
}